My boyfiend hit me accidentaly with the hand(palm) in the back of the head, i don t have pain, just fell sleppy.shoud i visit er?

Blackout? Dizzy?: If either happened, then, yes go to the er for an exam. Also if you have a continuing headache or nausea. If you are not sure, go to be most careful. If none of these things happened, and they do not bother you, you do not need to go to the er. For any questions, worsening of symptoms or if you just are not sure - then the safest way to be sure you are alright is to go to the er.

Yes.: Yes, you should go to the er as soon as possible. Also, i wonder if it was an accident or something that has happened before? Perhaps you should speak with a domestic violence counselor if it is something that happens frequently.